Relationship between Ra-226 activity concentration in building materials and indoor radon concentration: An example of Russian high-rise residential buildings

The worldwide trend toward the construction of high-rise buildings with high energy efficiency highlights the role of building materials as a source of indoor radon in the modern urban environment. The aim of the study is to analyze the relationship between the Ra-226 activity concentration in building materials and indoor radon concentration using the example of multi-story buildings in Ekaterinburg. Measurements of the activity concentration of natural radionuclides in building materials were carried out using a new non-destructive method. A radon survey conducted early provided the data on indoor radon concentrations in the same apartments. The obtained Ra-226 activity concentrations in building materials in high-rise buildings were found to be relatively low, ranging from 9.1 to 51 Bq/kg. The typical radon entry rate by diffusion from building materials for modern Russian multi-story buildings can be accepted as equal to 0.5 Bq/(m3∙h) per 1 Bq/kg of Ra-226 activity concentration. Ra-226 in building materials has been shown to be a primary source of indoor radon in modern high-rise buildings, where this factor can cause indoor radon concentrations above the reference level of 100 Bq/m3 at low air exchange rates. The activity concentration of Ra-226 in building materials should be considered a separate parameter for regulation within the national radiation protection systems.

COMPARISON OF MEASURES ON PROTECTION AGAINST ACCIDENTAL RADIATION AND INDOOR RADON EXPOSURE IN MUSLYUMOVO, TECHA RIVER

The objective of the study was comparison of the doses received due to contamination of the Techa River with those received from the indoor radon exposure. The study was performed on the example of Muslyumovo, the village closest to Mayak nuclear complex. The accidental doses were estimated using data on radionuclide intakes and ICRP-72 dose coefficients, and Techa River Dosimetry System. Radon exposure was estimated applying results of the radon surveys in 1992 and 2015. The doses prevented by means of different protection measures were considered. The maximum reduction of population exposure could be achieved in the case of timely evacuation to uncontaminated territory together with the indoor radon prevention measures.

Contemporary radiation doses to murine rodents inhabiting the most contaminated part of the EURT

The contemporary radiation doses to the organs and tissues of murine rodents inhabiting the most contaminated part of the EURT were estimated. The bones of animals trapped in 2005 at territories with a surface (90)Sr contamination of 24-40 MBq/m(2) were used for dose reconstruction. The concentration of (90)Sr in the animals' skulls was measured using the nondestructive method of bone radiometry. The dose estimation procedure included application of the published values of absorbed fractions of beta-radiation energy for different combinations of source and target organs, accounting for the distribution of radionuclide by organs and tissues. Twelve conversion coefficients were obtained to link the skeleton (90)Sr concentration and doses to eleven organs and the whole body. The whole-body dose rate on the 45th day after the beginning of exposure normalised to whole-body activity is 0.015 (mGy day(-1))/(Bq g(-1)). The estimation yields the following values of doses for Microtus agrestis, Sylvaemus uralensis and Clethrionomys rutilus, respectively: maximum absorbed doses in the skeleton: 267, 121 and 160 mGy; mean whole body internal doses: 37, 14 and 23 mGy; mean internal dose rates on the last day before trapping: 1.2; 0.44 and 0.75 mGy/day. Approaches to the assessment of doses to foetuses and to offspring before weaning were also developed.